It is, in fact, already well known to monitor pressure that is present in the interior of the tires of a motor vehicle. For this purpose, the monitoring systems known to date include, for example:    at the level of at least one wheel of the vehicle, a wheel module including an electronic module associated with an inflation valve of the tire and,    at the level of the passenger compartment of the vehicle, an electronic control unit.
Each electronic module includes in particular pressure sensors and temperature sensors, but may also include other sensors, for example acceleration sensors, shock sensors, etc., associated with a control unit equipped with at least one RF (Radio Frequency) transmitter and one LF (Low Frequency in the English language, for “Basses Fréquences”) receiver. Each electronic module also includes, in a manner known per se, storage means and a battery (for example a button cell).
The inflation valve associated with this electronic module is conventionally of two types. Either it is a metal inflation valve screwed into an opening in a wheel rim of the vehicle, or it is a “snap-in” valve (capable of elastic deformation) intended for insertion by force into the opening in the wheel rim by deformation of the elastic material forming its body. The present invention relates more specifically to a system for monitoring the pressure of the tires including an inflation valve known as a “snap-in” valve (capable of elastic deformation) associated with an electronic module for monitoring the pressure of the tires.
Such elastically deformable inflation valves exhibit the particularity of including a sealing groove, into which a wheel rim will be inserted when the valve is positioned on the wheel rim of the vehicle. In cross section, this sealing groove largely exhibits the form of a U and receives the wheel rim (steel/aluminum . . . ) in the interior of the two branches of the U. The part of the wheel rim that is received in the sealing groove is more or less thick according to the vehicle models and the choice of the wheel rim dimension. In a known manner, the majority of current wheel rims measure from 1.5 mm to 5 mm in thickness. For reasons of material costs, the most common thickness is in the order of 2 mm.
For reasons of reducing the cost of raw materials, but also in order to make the wheel rim lighter and to improve the performance of the vehicle with regard to fuel consumption, automobile designers would like to use increasingly thin wheel rims (thickness less than or equal to 1.5 mm). This reduction in the thickness of the wheel rim is possible only by optimizing the material utilized to produce this wheel rim, in particular by providing it with appropriate rigidity. However, by greatly reducing the thickness of the wheel rim, it behaves increasingly like a blade of a knife in continuous clamping contact with the elastic material of the sealing groove provided in the body of the inflation valve that is capable of elastic deformation (snap-in). This results in risks of shear ruptures (cutting) of the elastic material at the bottom of the sealing groove, leading in the long term to air leakage and a lack of sealing of the inflation valve. This should be avoided, of course.
The inflation valves that are capable of elastic deformation known to date thus exhibit substantially reduced service lives when they are used with wheel rims of small thicknesses (thickness less than 1.5 mm).